This invention relates in general to vehicle disc brake assemblies and in particular to an improved structure for a slide pin bushing adapted for use in such a vehicle disc brake assembly.
Most vehicles are equipped with a brake system for retarding or stopping movement of the vehicle in a controlled manner. A typical brake system for an automobile or light truck includes a disc brake assembly for each of the front wheels and either a drum brake assembly or a disc brake assembly for each of the rear wheels. The brake assemblies are actuated by hydraulic or pneumatic pressure generated when an operator of the vehicle depresses a brake pedal. The structures of these drum brake assemblies and disc brake assemblies, as well as the actuators therefor, are well known in the art.
A typical disc brake assembly includes a rotor which is secured to the wheel of the vehicle for rotation therewith. A caliper assembly is slidably supported by pins secured to an anchor plate. The anchor plate is secured to a non-rotatable component of the vehicle, such as the steering knuckle or axle flange. The caliper assembly includes a pair of brake pads which are disposed on opposite sides of the rotor. The brake pads are operatively connected to one or more hydraulically actuated pistons for movement between a non-braking position, wherein they are spaced apart from opposed braking surfaces of the rotor, and a braking position, wherein they are moved into frictional engagement with the opposed braking surfaces of the rotor. When the operator of the vehicle depresses the brake pedal, the piston urges the brake pads from the non-braking position to the braking position so as to frictionally engage the opposed braking surfaces of the rotor and thereby slow or stop the rotation of the associated wheel of the vehicle.
As mentioned above, the caliper assembly is slidably supported on pins secured to the anchor plate. A typical pin includes a non-threaded main body and threaded end. The main body of the pin extends into a non-threaded opening formed in the inboard leg of the caliper, and the threaded end of the pin is received in a threaded opening provided in the anchor plate. Since the pins slidably support the caliper assembly relative to the anchor plate, it is important that the caliper assembly is sufficiently supported by the pins while still being able to freely slide. Thus, it is known to provide the disc brake assembly with a hollow cylindrical metal sleeve or bushing which is disposed in the non-threaded opening of the inboard leg of the caliper about the non-threaded main body of the pin. Also, in order to prevent debris from entering, a rubber slide pin bushing is disposed in the non-threaded opening formed in the inboard leg of the caliper about the outer diameter of the metal sleeve. U.S. Pat. No. 4,331,221 to Evans discloses such a known pin, slide pin bushing, and metal sleeve for use in a disc brake assembly.